Adherent rubber composition for steel cord

Abstract

An adherent rubber composition suitable for use in the adhesion to steel cords comprises given amounts of an inorganic salt hydrate and sulfur based on 100 parts by weight of rubber ingredient comprising not less than 10% by weight of at least one synthetic rubber and the remainder being natural rubber.

What is claimed is: 
     
       1. An article comprising a steel cord and a vulcanized rubber composition adhered to said steel cord; said rubber composition comprising 0.1-10 parts by weight of an inorganic salt hydrate selected from the group consisting of Na  2  S·9H 2  O, Na 3  PO 4  ·12H 2  O, NaH 2  PO 4  ·12H 2  O, Na 2  HPO 4  ·12H 2  O, Ni 3  (PO 4 ) 2  ·8H 2  O, Mg 3  (PO 4 ) 2  ·8H 2  O, Li 3  PO 4  5H 2  O, Na 4  P 2  O 7  ·10H 2  O, Ni 2  P 2  O 7  ·6H 2  O, Mn 4  (P 2  O 7 ) 3  ·14H 2  O, CoCO 3  ·6H 2  O, NiCO 3  ·6H 2  O, Na 2  CO 3  10H 2  O, Nd 2  (CO 3 ) 3  ·8H 2  O, and Na 2  SiO 3  ·9H 2  O, and 3-8 parts by weight of sulfur based on 100 parts by weight of rubber ingredient comprising at least one rubber selected from the group consisting of natural rubber and synthetic rubber. 
     
     
       2. The article according to claim 1, wherein the rubber ingredient contains at least 50% by weight of natural rubber. 
     
     
       3. The article according to claim 1, wherein the synthetic rubber is selected from the group consisting of styrene-butadiene rubber, butadiene rubber, butyl rubber, halogenated butyl rubber, butyl rubber having a paramethylstyrene group therein, isoprene rubber and ethylene-propylene-diene rubber. 
     
     
       4. The article according to claim 1, wherein the rubber composition further contains 2-10 parts by weight of zinc white, 0.3-2 parts by weight of a vulcanization accelerator, 0.25-3 parts by weight of an adhesion promoter and 30-70 parts by weight of carbon black based on 100 parts by weight of the rubber ingredient. 
     
     
       5. The article according to claim 4, wherein the styrene-butadiene rubber is a solution-polymerized styrene-butadiene rubber having a vinyl content of 35-85% by weight and a bound styrene content of not more than 30% by weight, and the butadiene rubber has a vinyl content of 1-85% by weight. 
     
     
       6. The article according to claim 1, wherein the amount of the inorganic salt hydrate is 0.2-8 parts by weight. 
     
     
       7. The article according to claim 1, wherein the amount of the inorganic salt hydrate is 0.3-3 parts of weight. 
     
     
       8. The article according to claim 1, wherein the inorganic salt hydrate is Na 4  P 2  O 7  ·10H 2  O or Na 2  SiO 3  ·9H 2  O. 
     
     
       9. The article according to claim 1, wherein the steel cord is brass plated. 
     
     
       10. The article according to claim 1, wherein the Cu content of the brass plating is not more than 75% by weight. 
     
     
       11. The article according to claim 10, wherein the Cu content of the brass plating is not more than 55-70% by weight. 
     
     
       12. The article according to claim 1, wherein the article is a tire or a conveyer belt. 
     
     
       13. The article according to claim 1, wherein the article is a tire.